Liquid petroleum gas agitator



Sept. 13, 1955 D. G. FIKE LIQUID PETROLEUM GAS AGITATOR Filed June 4, 1954 22 a a [29 f* Wye/m2,"

Unite This invention relates to liquefied petroleum gas systems for farm homes and the like. It has particular application to horizontally disposed, permanent tank installations, although its use is not confined thereto.

One of the difficulties experienced in the use of liquefied gases of the character used for domestic heating and cooking, especially in relatively large, permanenttype gas tank installations, arises from the fact that the heavier and less volatile fractions of the gas, both in the gaseous and liquid phases, tend to settle. There is also a safety problem in that frequently the odorant added to the liquid also tends to settle, so that the odor of the lighter fractions is less pronounced than that of the heavier fractions. While all of the fractions are usable, the vertical stratification of gas and liquid produces differences in the combustion of the gas at a burner. Thus, the proper ratio of air to gas at the burner for a freshly filled tank of gas may be entirely wrong for a tank which is nearly spent.

One of the objects of this invention is to provide a simple means for agitating the liquid in a liquefied petroleum gas tank to provide gas of substantially uniform character at every stage as the tank is emptied.

Other objects will become apparent to those skilled in the art in the light of the following disclosure and accompanying drawing.

It has been observed that in liquefied petroleum gas tanks in which there is a pool of liquid under pressure, there is a definite temperature gradient between the top of the tank, which contains gas, and the lower part of the tank, which contains liquid. When large quantities of gas are being used, as when the gas is being used for space heating, the liquid, frequently becomes so chilled as to cause frost to form on the outside of the tank, even in warm weather.

In accordance with this invention, generally stated, the difference in temperature between the upper and lower parts of the tank is utilized to produce a thermal agitation of the liquid in the tank.

In particular, the gas being withdrawn is led through heat-conducting tubing below the surface of the liquid in such a way as to create convection currents in the liquid.

In the drawing, Figure 1 is a view in side elevation of a horizontal, liquefied petroleum gas tank and supply line leading to a home gas appliance;

Figure 2 is a view partly in section of the tank shown in Figure 1, showing an agitating coil constructed in accordance with one embodiment of this invention; and

Figure 3 is a sectional view taken along the line 3-3 of Figure 2.

Referring now to the drawing for an illustrative embodiment of this invention, reference numeral 1 represents a horizontal tank containing LP gas. The term LP gas will be used hereafter to indicate liquefied petroleum gases. The term liquefied petroleum gas is used in the trade to include propane, butane, and various mixed hydrocarbonaceous gases.

The tank 1 is supported by legs 2 on a base 3. The

States Patent 2,717,493 Pate ed Sep 13., 1.95.5

ice

tank 1 is provided with a head. 4., on which a'eover 5; is removably mounted. The head 4 carries various valves and fittings, including a filling port 8 through. whi h liquefied gas is introduced to the tank, a liquid level gauge. 10 and an outlet port 12 with a pressure regulating (reducing) valve 13.

The tank 1 contains a pool of liquid, gas 25,, above which is a chamber 26 filled with gas under pressure.

In the embodiment shown, a coil 15, of heataco duct ing g; su h as, pp ing. is conn cted at o of its ends 17 to the outlet port 12. From the end 17, the coil extends in turns 18, which are only slightly smaller in diameter than the inside diameter of the tank 1, through substantially the full length of the tank. The coil 15 terminates at an open end 20 which is positioned in the chamber 26 above the highest level to which the pool of liquid gas ever extends. In the embodiment shown, the end 20 of the coil is mounted in a bracket 22, secured to the inside surface of the tank.

In the operation of this embodiment, when a valve connected with the outlet 12 is opened to permit the escape of gas, the gas is forced by the pressure in the tank through the open end 20 of the coil, through all of the turns of the coil and out through the end 17 of the coil.

The gas in the upper part of the tank is substantially warmer than the liquid 25 and also warmer than the layer of gas contiguous to the liquid. Because of the position of the open end 20 of the coil 15, this relatively warm gas is forced into the open end 20 and passed alternately below the surface of the liquid and into the gas-containing chamber above the liquid. In its passage through the liquid, the gas gives up a part of its heat, through the heat-conducting walls of the tubing, to the liquid. At the same time, as the temperature of the gas in the coil is lowered, it tends to absorb heat from the ambient gas in the upper part of the tank. Thus, the liquid is warmed in spaced areas through substantially the length of the tank while the gas in the upper part of the tank is cooled, particularly at the end of the tank farthest from the end 20 of the coil.

As the liquid is warmed, convection currents are set up which effectively mix the various components of the liquid. At the same time, the cooling of the gas in the upper part of the tank sets up convection currents in the gas.

It can be seen that other arrangements of the coil 15 may be used. For example, with the inlet end 20 of the tube in the same position, the coil can take the form of a multiplicity of flat loops the reaches of which are substantially horizontal and run axially of the tank below the surface of the liquid, with the loop immediately following the end 20 being positioned at the lowermost part of the tank. One or more of the loops may extend within the gas-filled chamber.

It has been found, however, that the embodiment illustrated is preferable, for several reasons. It is simple to fabricate and install, being self-sustaining when permitted to rest on the bottom. In addition, the illustrated embodiment produces temperature gradients both vertically and axially in the tank, giving efiective agitation. Also, the coils of the preferred embodiment may be spaced to permit the ready insertion and operation of the liquid level gauge.

It can be seen that the device also has application to vertically disposed tanks. It is only necessary to position the inlet 20 within the upper, gas-filled part of the vertical tank, to lead the coil from the inlet 20 to a position adjacent the bottom of the tank, and to lead the outlet end of the coil back to the upper part.

The tubing of the coil may be made of any suitable material, copper tubing being used in the illustrative embodiment only because it is a standard, easily obtained, readily worked, heat-conducting material.

Having thus described the invention, what is claimed and desired to be secured by Letters Patent is:

1. In a liquefied petroleum gas tank containing a pool of volatile liquid and a chamber of gas under pressure above said pool, there being a temperature gradient between the relatively warm upper, gas-filled part of said tank and the lower, relatively cold liquid-filled part of said tank, the improvement comprising a coil of heat-conducting tubing one end of which is open and positioned within.

the chamber above said pool and the other end of which is directly connected to a gas outlet, said coil, intermediate its ends, extending in a multiplicity of loops through said pool and through said gas-filled part of said tank, whereby transfer of heat from said gas in said coil to the liquid in said pool is effected.

2. The improvement of claim 1 wherein the coil takes the form of a multiplicity of circular loops closely adjacent the inside surface of the tank, and extending spirally through substantially the full length of the tank.

References Cited in the file of this patent iii. 

